1. Field of the Invention
The present invention relates to a global positioning system receiver (GPS receiver), and particularly to a power saving device and a method thereof for a GPS receiver.
2. Description of Related Art
Conventionally, the location of a GPS receiver is calculated by means of the GPS receiver receiving positional data sent by at least four GPS satellites. Because the GPS receiver is getting popular, it is widely applied for guiding a vehicle and registering a moving track thereof. In order to offer the vehicle a correct position constantly, the GPS receiver has to be in a state of alert and the power is wasteful.
The U.S. Pat. No. 5,592,173 discloses a GPS receiver having a low power standby mode, which allows the user to select the standby mode of the GPS receiver for saving the power in accordance with the correlation information and location information provided by a microprocessor.
Although the power saving for the GPS receiver can be performed by standby mode switched manually in the preceding U.S. Patent, a much better effect for saving the power can be attained if the GPS receiver is turned on or off automatically in accordance with the vehicle in a actual state of stopping or moving.
For instance, the GPS receiver is shut during the vehicle stopping and is started at the moment ready for moving. Further, the GPS receiver is turned off and on a time interval of five minutes alternately in case of the vehicle is moving in a high speed for a long duration such as being driven an hour continuously with a speed exceeding 80 Km/hour and then the GPS receiver can be shut at the time of receiving a positional data. Under this condition, a function of saving power also can be obtained without affecting the guidance of vehicle and the moving track register.
A primary object of the present invention is to provide a power saving device for a GPS receiver, which can start to run automatically during the GPS receiver generating vibration due to moving and be off automatically during the GPS receiver being stationary due to stop moving.
Another object of the present invention is to provide a power saving method for a GPS receiver, with which the GPS receiver can be controlled to turn off and turn on after a time interval sequentially during a vehicle moving a long period of time and the moving speed thereof exceeding a preset value.